A volume discount is automatically applied to a Shopify order based on the quantity of books ordered for each individual product. 

For example, if one of your customers purchases 100 copies of one product and 15 copies of another product in a single order, a discount will be applied to the 100 copies, but not the 15 copies. If a customer purchases 15 copies of each product, no discount will be applied.

Note: Lulu Direct does not apply automatic discounting to your customers. As the store owner, you can apply discounts through your Shopify store as you see fit.